I don't think it is ruined - try it and see. If the citric acid concentration the way you have added it is greater than what they intended in the instructions, the solution should be less contrasty, requiring a more dense negative for best results.
I don't know how or how fast the stock will go bad with citric acid added, but here is a hint or two I've read and personally confirmed
When you coat it and let it dry, the coating should be yellow. If it is noticably green or worse, blue, the print will be fogged, since the color shift is due to some of the chemicals already converting to Prussian Blue.
I've mixed the sensitizer from raw chemicals, so I am varying the dichromate concentration, which does increase the sensitizer concentration, but I just recently got some citric acid, and haven't tried it yet, either in the sensitizer or as a first bath.
I have problems with slight fogging, so next time I print cyanotypes, I am going to try adding citric acid - I've got 10 5x7 negatives to develop for cyanotypes on my 'to do list'
I'm still working toward a cyanotype I am totally happy with but I'll post my first 'decent' cyanotype in my gallery.
Two sites I've found useful for 'New' Cyanotype are Mike Ware's site:
http://www.mikeware.co.uk and
http://www.wynnwhitephoto.com/cyan_notes.html - Wynn White's notes on New Cyanotype printing.
Jon